Glass keyboard, and method for producing a glass keyboard

ABSTRACT

In a glass keyboard comprising a keyboard surface ( 4 ) made from a flexible thin glass pane ( 2 ) and at least one carrier material pane ( 6 ), each pane being provided with an electroconductive layer ( 8,10 ) on the faces facing each other, wherein the opposing electroconductive layers ( 8,10 ) are kept at a distance to each other with the aid of a spacer ( 12 ), and wherein the electroconductive layers ( 8,10 ) touch each other when pressure is applied to the flexible thin glass layer ( 2 ) at the essentially localized place of pressure application, it is provided that the electroconductive layers ( 8,10 ) on the thin glass pane ( 2 ) and the carrier material pane ( 6 ) are connected with conductors ( 62,66 ) which are led out at a side edge of the keyboard surface ( 4 ), that a flexible flat multiple cable ( 64,68 ) is connected with the conductors ( 62,66 ) of the electroconductive layers ( 8,10 ) via contacts ( 74,75 ), and that the flat multiple cable ( 64,68 ) comprising the contacts ( 74,75 ) is arranged between the thin glass pane ( 2 ) and the carrier material pane ( 6 ).

The present invention relates to a glass keyboard and to a method forproducing a glass keyboard.

BACKGROUND OF THE INVENTION

Such pressure switch elements are known as touch panels in displays. Thetouch panels are normally made from transparent plastic films whoseinner surfaces are coated with an electroconductive material. To supportsaid films spacers are glued in the air gap, wherein a spacer arrangedaround the outside of the contact area is bonded in an airtight mannerto the plastic films to stabilize the inside air pressure thussupporting the upper film. Inside the contact area elastic spacers areadditionally provided which ensure return movement of the films. It is adrawback of the known pressure switch element that it requires ahermetically sealed air space which does not allow for any pressurecompensation. In the event of considerable deviation from the normalatmospheric pressure, e.g. during application in submarine vehicles orin aeronautics and space operations, and at high temperatures hairlinecracks occur in the vapour-deposited electroconductive contact layer dueto the changes in air pressure, which results in a failure of the unit.At large heights the spacer in the contact area expands. This changesthe switching path of the contact film, and the given electronical andmechanical parameters, such as the action point, are no longer compliedwith. Further drawbacks of the known touch panels are that the plasticfilms present only a limited mechanical and chemical resistance, a-smalldegree of transmission and are not antistatic. Further, in the event oftemperature variation there is the danger of crack formation in theelectroconductive layer due to fact that the expansion coefficients ofthe conductive layer and the plastic carrier considerably differ fromeach other.

From EP 0 546 003 B1 a pressure switch element made from a glasslaminate is known which comprises a flexible thin glass pane and atleast one carrier glass pane, each pane being provided with anelectroconductive layer on the faces facing each other. The opposingelectroconductive layers are kept at a distance to each other with theaid of a spacer. The electroconductive layers touch each other whenpressure is applied to the flexible thin glass layer at the essentiallylocalized place of pressure load application.

With regard to this type of pressure switch element it is commonpractice to provide the electrode connections of the electroconductivelayers at a protruding edge of the carrier material pane.

For this purpose the electroconductive layer on the thin glass pane isbonded to the thicker carrier glass pane via an electroconductive spacerand then glued to a flexible multiple cable at the protruding edge. Itis a drawback that microcracks occur due to the membrane effect of thethin glass pane when pressure is applied to the electroconductivespacer, which may lead to malfunction.

SUMMARY OF THE INVENTION

It is the object of the invention to provide a glass keyboard which canbe produced at less expenditure and presents high contact reliabilitywith regard to the electrical connections.

According to the invention the electroconductive layers on the thinglass pane and the carrier material pane are preferably connected withconductors which are led out at a side edge of the keyboard surface,that a flexible flat multiple cable is electrically connected with theconductors on the thin glass pane and the carrier material pane, andthat the flat multiple cable is arranged between the thin glass pane andthe carrier material pane.

In this way the conductors of the thin glass pane are bonded in aprotected area within the glass keyboard with the flat multiple cablebeing insulatingly coated on the side averting the conductors.

The invention further provides a method for producing glass keyboardswhere a thin glass pane is glued at a distance to the carrier materialpane with a flat multiple cable being connected,-simultaneously on twoplanes, in a contact-proof and break-proof manner with theelectroconductive layers.

Preferably a first flat multiple cable is electroconductingly glued tothe thin glass pane while a second flat multiple cable iselectroconductingly glued to the carrier material pane. On each rearside the film-type flat multiple cable is insulated.

The thickness of the film-type flat multiple cable corresponds to thethickness of the spacer preferably made up of an adhesive arrangedbetween the thin glass pane and the carrier material pane such that theflat multiple cables may preferably be inserted at a side edge of theglass keyboard so as to act as spacers.

The flat multiple cables are arranged at a lateral distance to eachother between the thin glass pane and the carrier material pane. Thegaps are filled with an adhesive, preferably a plastic material curedunder UV-light.

Between the contacts connected with the conductors of a flat multiplecable, too, recesses may be left. Said recesses are also filled with anadhesive cured under UV-light. Due to the glueing in the recesses andthe gaps mechanical pressure in this area of the thin glass pane doesnot lead to cracking of the glass since the adhesive serves as a spacerand further compensates for different film material thicknesses of theflat multiple cables.

The flat multiple cables are connected at their free ends with amultiple plug connector. A microprocessor may be integrated in the flatmultiple cables or in the multiple plug connector.

According to a preferred aspect the carrier material pane is slightlylarger than the flexible thin glass pane such that the marginal area ofthe carrier material pane protrudes beyond the the marginal area of thethin glass pane. The protruding marginal area of the carrier materialpane protects the sensitive marginal edge of the thin glass pane, whichcan further reduce the danger of breakage of the thin glass pane.

The the flat set back margin of the thin glass pane is glued to themarginal area of the carrier material pane by means of an adhesiveacting as a spacer in the marginal area. The protruding margin of thecarrier material pane is further adapted to receive an adhesive build-upwhich also protects the sensitive edge of the thin glass pane.

Preferably the margin of the thin glass pane is stabilized by means of acured plastic material. The cutting edge of the thin glass pane displaysa plurality of microcracks which occur during the cutting process andextend from the edge to the inside. Said microcracks may easily resultin a crack which destroys the entire thin glass pane. The margin of thethin glass pane is therefore preferably stabilized by means of a curedplastic material. For this purpose the boundary edges of the thin glasspane are dipped into a liquid plastic material. Due to the capillaryeffect the microcracks are filled with the liquid plastic materialwhereafter the plastic material cures. When the plastic material iscured, the thin glass pane offers a considerably higher stability sincebreaking of the thin glass pane starting from its margins can no longeroccur in the event of pressure or shock load.

The thickness of the thin glass pane ranges between approximately 0.1and 0.5 mm, preferably between approximately 0.175 and 0.4 mm. A thinglass pane of such a thickness offers an adequate flexibility to allowfor localized switching contact between opposing electroconductivelayers.

The spacer is arranged exclusively in the marginal area of the keyboardsurface between the thin glass pane and the carrier material pane,wherein in the remaining portion of the keyboard surface switchingoperations can be performed formed at any location without furtherspacers being provided. The invention preferably makes additionalspacers in the area of the switching section superfluous such that theoverall keyboard surface is available for switching operations withoutany limitations.

In a preferred embodiment the spacer in the marginal area is made from aplastic material cured under UV-light. This offers the advantage that noseparate spacer has to be provided, and that the spacer can already beformed when the thin glass pane is glued to the carrier material pane.

The carrier material pane and/or the spacer comprise in the marginalarea vent openings for the space between the thin glass pane and thecarrier material pane. This offers the advantage that pressurecompensation is possible in the event of deviation from the normalatmospheric pressure, e.g. during application in submarine vehicles orin aeronautics and space operations, and at high temperatures such thatthe electroconductive layers on the thin glass pane and the carriermaterial pane are prevented from being damaged.

The vent openings are preferably provided with a filter materialprotecting the glass keyboard from soiling.

Further preferred features of the invention are stated in the subclaims.

Hereunder embodiments of the invention are explained in detail withreference to the drawings in which:

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 shows the glass keyboard according to the invention,

FIG. 2 shows a cross-section of the glass keyboard of shown in FIG. 1,

FIG. 3 shows a side edge of the glass keyboard with conductorconnections,

FIG. 4 shows the glueing together of the glass keyboard, and

FIG. 5 shows a flat multiple cable acting as a spacer between thin glasspane and carrier material pane.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The glass keyboard shown in FIGS. 1 and 2 comprises a relatively thicklower carrier material pane 6 and a thin glass pane 2 kept at a paralleldistance to the carrier material pane 6 with the aid of a spacer 12. Thethin glass pane 2 and the carrier material pane 6 are provided withelectroconductive layers 8,10 on the opposing inner faces, theelectroconductive layers 8,10 forming electrodes and establishing aswitching contact when the layers touch each other. For this purpose theflexible thin glass pane 2 may be deformed by essentially localizedpressure application such that an electric contact is establishedbetween the conductive layers 8,10.

Such a configuration of the glass keyboard can be employed for bothanalog glass keyboards where the electroconductive layers 8,10essentially cover the entire keyboard surface 4, and digital glasskeyboards where the electroconductive layers 8,10 are structured andcomprise e.g. a plurality of conductors arranged parallel to each other.The conductors on the electroconductive layer 8 are preferably arrangedat right angles to the conductors on the electroconductive layer 10. Forthe purpose of simplification only the connections 62,66 of theconductors are shown in the drawings.

The thin glass pane 2 is cut out of a drawn thin glass film and has athickness ranging, between approximately 0.1 and 0.5 mm, preferablybetween approximately 0.175 and 0.4 mm. Float glass of the samethickness comprises a tin film which leads to embrittlement of the glassand is thus not suitable for this application. Only thin glass panesproduced from a drawn glass film have an adequate flexibility andbreaking strength which allow even larger keyboard surfaces 4 to beproduced. Further, the glass thickness must be uniform to a high degree.

The thin glass pane 2 has a slight convexity to the outside and is gluedin this condition to the carrier material pane 6 using the spacer 12.For this purpose the thin glass pane 2 is deep drawn with thereremaining a flat marginal area 20. The spacer is preferably formed bythe adhesive glueing the two panes 2,6 together with glueing beingcarried out only at the edge of the marginal area 20 of the thin glasspane 2. The carrier material pane 6 protrudes on all sides beyond thethin glass pane 2 thus allowing for effective protection of thesensitive outer edges of the thin glass pane 2. At the same time theprotruding margin of the carrier material pane 6 forms a supportingsurface for an adhesive build-up 14 which reaches up to the upper edgeof the thin glass pane 2. Said adhesive build-up 14 additionallyprotects the sensitive outer edge of the thin glass pane 2.

The convexity of the thin glass pane 2 to the outside offers theadvantage that higher return movement forces are produced, and that thethin glass pane 2 does not require further spacers to be arranged in thearea of the keyboard surface 4. It is important that no spacers areprovided in the switching area 24 of the keyboard surface 4 since itwould not be possible to establish a switching contact in the area ofsuch spacers. The glass keyboard described here can be operated at anylocation of the keyboard surface 4.

Another advantage of the convexity of the thin glass pane 2 to theoutside is that the formation of Newton's rings, which are undesired intransparent keyboards, is prevented.

The thin glass pane 2 may be edge-stabilized. Edge stabilizing isrealized by dipping the cutting edges of the thin glass pane 2 cut outof a drawn thin glass film into a highly viscous curable plasticmaterial. The adhesive has several functions, i.e. it acts as a spacer12 between the thin glass pane 2 and the carrier material pane 6, itacts as edge stabilizer-by penetrating the microcracks in the edge area20 of the thin glass pane 2, and it acts as outer edge protection forthe thin glass pane 2 by forming an adhesive build-up 14 on theprotruding margin of the carrier material pane 6. The adhesive build-up14 is preferably produced in a second working cycle.

The margin of the carrier material pane 6 protrudes beyond the outeredges of the thin glass pane 2 by e.g. approximately 1 mm thus forming,in conjunction with the adhesive build-up 14, an effective protectionagainst shocks on the outer margin of the glass keyboard.

A plastic material curing under UV-light is preferably used as adhesive.Such an adhesive offers the advantage that the time of curing can beexactly controlled, which considerably facilitates the productionprocess.

FIG. 3 shows the side edges of the carrier material pane 6 and the thinglass pane 2 with the conductors 62,66 ending in the edge areas 20 and28 respectively, the conductors 62,66 forming the connecting lines ofthe electroconductive layers 8,10.

The conductors 62,66 may be glued to connecting contacts 74,75 at theend of flexible film-type flat multiple cables. As shown in FIG. 3 oneflat multiple cable 64,68 each is preferably provided for both thecarrier material pane 6 and the thin glass pane 2. It is however alsopossible to provide only one film-type flat multiple cable comprisingcontacts 74,75 at both ends such that only one flat multiple cable canbe bonded both to the thin glass pane 2 and the carrier material pane 6.In this connection it may be envisaged that in the case of opposingcontacts 74,75 the contacts for the thin glass pane 2 are insulated fromthe contacts 75 for the carrier material pane 6 by means of aninsulating intermediate layer.

In the embodiment shown in FIG. 3 the flat multiple cable 64 iselectroconductingly glued to the thin glass pane 2 while the flatmultiple cable 68 is electroconductingly glued to the carrier materialpane 6. Preferably the flat multiple cables 64,68 are glued to therespective pane 2,6 prior to joining the carrier material pane 6 and thethin glass pane 2. In a second step the two panes 2,6 are then glued toeach other in the usual manner. The recesses 70 are filled with adhesivewhich forms a spacer together with the bonding ends of the flat multiplecables 64,68.

Although a preferred embodiment of the invention has been specificallyillustrated and described herein, it is to be understood that minorvariations may be made in the apparatus without departing from thespirit and scope of the invention, as defined the appended claims.

The flat multiple cables 64,68 are connected to a multiple plugconnector 72 which may comprise two multipoint connectors adapted to befitted together such that each flat multiple-cable is connected to amultipoint connector.

A microprocessor 76 may be integrated in the flat multiple cable or inthe plug connector, the microprocessor 76 containing a control unit forthe glass keyboard.

What is claimed is:
 1. A glass keyboard comprising a keyboard surface(4) made from a flexible thin glass pane (2) and at least one carriermaterial pane (6), each pane being provided on opposing faces with anelectroconductive layer (8, 10), the opposing electroconductive layers(8, 10) being kept at a distance from each other by a spacer (12), theelectroconductive layers (8, 10) touch each other when pressure isapplied to the flexible thin glass pane (2) at an essentially localizedarea of pressure application, the electroconductive layers (8, 10) onthe thin glass pane (2) and the carrier material pane (6) beingconnected with respective conductors (62, 66) which are led out at aside edge of the keyboard surface (4), flexible flat multiple cables(64, 68) being connected respectively with the conductors (62, 66) ofthe electroconductive layers (8, 10) via contacts (74, 75),the flatmultiple cables (64, 68) and the contacts (74, 75) being arrangedbetween the thin glass pane (2) and the carrier material pane (6), andthe flat multiple cables (64, 68) are in side-by-side relationship toeach other.
 2. Glass keyboard according to claim 1 characterized in thatthe flat multiple cables (64,68) have a thickness corresponding to thethickness of the spacer (12).
 3. Glass keyboard according to claim 1characterized in that between the contacts (74) connected with theconductors (62,66) of a flat multiple cable (68) recesses (70) are leftopen.
 4. Glass keyboard according to claim 1 characterized in that amicroprocessor (76) is integrated in a flat multiple cable (64,68). 5.Glass keyboard according to claim 1 characterized in that the carriermaterial pane (6) is slightly larger than the flexible thin glass pane(2) such that the marginal area (28) of the carrier material pane (6)protrudes on all sides beyond the marginal area (20) of the thin glasspane (2).
 6. Glass keyboard according to claim 1 characterized in thatthe margin of the thin glass pane (2) is stabilized by means of a curedplastic material (16).
 7. Glass keyboard according to claim 1characterized in that the keyboard surface (4) made from the flexiblethin glass pane (2) is of flat configuration in the marginal area (20)and displays a slight convexity-to the outside in the switching area(24).
 8. Glass keyboard according to claim 1 characterized in that thethickness of the thin glass pane (2) ranges between approximately 0.1and approximately 0.5 mm, preferably between 0.175 and 0.4 mm.
 9. Glasskeyboard according to claim 1 characterized in that the spacer (12) isarranged exclusively in the marginal area (20,28) of the keyboardsurface (4) between the thin glass pane (2) and the carrier materialpane (6), and that the remaining portion of the keyboard surface isadapted for localized switching at any location without any furtherspacer being provided.
 10. Glass keyboard according to claim 1characterized in that the spacer (12) in the marginal area is formed bya plastic material curing under UV-light.
 11. Glass keyboard accordingto claim 1 characterized in that at the free end of the flat multiplecables (64,68) a multiple plug connector (72) is connected.
 12. Glasskeyboard according to claim 11 characterized in that the microprocessor(76) is integrated in the multiple plug connector (72).
 13. The glasskeyboard according to claim 1 characterized in that the conductors (62)are on the thin glass pane (2), and the conductors (66) are on thecarrier material pane (6).
 14. Glass keyboard according to claim 13characterized in that the first flat multiple cable (64) iselectroconductingly glued to the thin glass pane (2) and the second flatmultiple cable (68) is electroconductingly glued to the carrier materialpane (6).
 15. Glass keyboard according to claim 13 characterized in thatthe flat multiple cables (64,68) are arranged at a lateral distance toeach other between the thin glass pane (2) and the carrier material pane(6).
 16. A method of producing a glass keyboard comprising the steps ofproviding a keyboard surface (4) made from a flexible thin glass pane(2) and at least one carrier material pane (6), the panes having anelectroconductive layer (8, 10) on respective faces facing each other,maintaining the opposing electroconductive layers (8, 10) at a distanceto each other by a spacer (12), effecting contact between theelectroconductive layers (8, 10) by applying pressure to the flexiblethin glass pane (2) at an essentially localized area of pressureapplication, leading the electroconductive layers (8, 10) peripherallyoutwardly from between the thin glass pane (2) and the carrier materialpane (6) by conductors (62, 66) at a side edge of the keyboard surface(4), electrically connecting flexible flat multiple side-by-side cables(64, 68) respectively with the conductors (62, 66) of the thin glasspane (2) and the carrier material pane (6) and gluing the flexible flatmultiple cables (64, 68) respectively to the thin glass pane (2) and thecarrier material pane (6), and subsequently gluing the thin glass pane(2) and the carrier material pane (6) to each other using an adhesive asa spacer (12) which at least in part sets-off gaps in each of which ishoused conductors (74, 75) of said respective flat multiple cables (64,68).
 17. Method according to claim 16 characterized in that the flatmultiple cables (64,68) are used as spacer (12) in the marginal area(20,28) of the thin glass pane (2) and the carrier material pane (6).18. Method according to claim 16 characterized in that the outer edge inthe marginal area (20) of the thin glass pane (2) is stabilized by meansof a highly viscous and quick-curing plastic material (16) prior tojoining the thin glass pane (2) and the carrier material pane (6). 19.Method according to claim 16 characterized in that the carrier materialpane (6) is cut so as to be slightly larger than the flexible thin glasspane (2) such that the marginal area (28) of the carrier material pane(6) protrudes beyond the marginal area (20) of the thin glass pane (2).